Automatic electric switch



H. A. HUESCHEN.

AUTOMATIC ELECTRIC SWITCH.

APPLICATION FILED MAR. 31, 1919.

Patented Jan. 25.1921.-

2 SHEETS-SHEET 1.

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HENRY A. HoEscH EN un/imam:

H. A. HOESCHEN.

AUTOMATIC ELECTRIC SWITCH.

APPLICATION FILED MAR. 31. I9I9I 1,366,731. Patented Jan. 2 21.

2 SHEETS-S HENRY A. HOESCHEN UNITED STATES PATENT OFFICE.

HENRY A. HOESCHEN, OF OMAHA, NEBRASKA, ASSIGNOR OE ONE-HALE '10 BAKER ICE MACHINE COMPANY, OF OMAHA, NEBRASKA, A CORPORATION OF NEBRASKA.

AUTOMATIC ELECTRIC SWITCH;

Specification of Letters Eatent. Patented J 25 1921- -App11bation filed March 31, 1919. Serial ,No. 286,559.

To all whom it may concern: a

. Be it known that I, HENRY A. HOESCHEN,

a citizen of the United States, and a resident of Omaha, in the county of Douglas and State of Nebraska, have invented certain new and. useful Improvements in Automatic Electric Switches, of which the following is a specification. 4

My invention relates to electrically actuated and controlled switches, for use in motor-circuits and the like, wherein it is' desirable that the motor-circuit be opened and closed automatically to stop and start the motor, or to stop and start the operationof other electrically operated devices, in accordance with conditions which are varied bythe operation of the motor or other device controlled by the switch. It is theoloject' of my'invention to provide an eflicient anddurable automatic switch, suitable for use in opening and closing circuits carrying heavy currents of moderate voltage, wherein the switch is actuated by a single solenoid,

said solenoid energized ,by control-circuits,

automatically and closed alternately with each and the control circuits opened other. A. further object of my invention is to provide means for mechanically holdin the main-switch brushes in engagement wit their contacts when the switch is in closed position, said holding means being 'yield'able" and having a maximumxpower when the switch is closed, and said holding means having-a continued tendency tomove theswitch toclosed position,vbut the tendency}- being variable non-uniformly. .A' further.

object of my invention is'to providea con-f trol-,sWitcl1 for establishing the control-cir-Y said control-switch being 40 actuated only at ,the conclusion" {of those" movements ofthe solenoid-core necessary for efiecting the opening and closing of the More particular ob ects of, y

' -tact-posts aresli Tat their 'inner e ges,-and' the arrangement t'of the brush-platesis such that theyassume a" downwardly bowed form when the switch cuits alternately,

main-switch. my invention will appearfhereinaftenh In the accompanying drawings Figuretherefor represented diagrammatically-{and 5 tion, Fig.2 is a deta-i the closing-springfi for tii'efivarieble-tensioq 1- 4 device, Fig; Sis adetail ammun tio main-switch contact- ,o sts,- "on-the ne;

of Fig. 4, Fig, 4 is a rontfview sliowinfi-nthe .by screws 13 extendin other'by means of laminated brushes,

' graduated lengths, and

the main switch bein shown in osh l' front 'viewjof 'on B of a on the line 7-7 of Fig. 4:-

In carrying out my invention according to the illustrated embodiment thereof, I provide a base or support 8 comprising a slab of insulating material, such as slate or marble, disposed in a vertical position. .On said base 8 the main-switch contact-posts 9, 10, 11 and 12 are arranged in pairs at opposite sides of and symmetrical to the center-line of the front face of the base-slab. Said contact-posts are'secured to the base through the slab from baclrto front, as s own in Fi 3, and are connected respectively with bindingposts 14, 15, 16 and 17, by suitable conductors indicated by dotted lines in Fig; l. Feed-wires from a suitable generator G may be connected. with the binding-posts 14C and 15, and a motor M, or the like, similarly connected with the binding posts 16 and 17. The. airs of contact-posts 911 and 10-42 are p aced in electrical connection with each;

each

comprising a series of normally flat plates 18,119, 20' and 21',- ofresilient electrically 4 conductive material, said plates'being of v the end-portionsof; the, shorter plates being longitudinally kerfed or slitted, as shown in Fig'.5,*toforrn*T a series of independently-yieldable'fingersf; for engagement with theflat faces oftheffl contact-post's! v 7 preferably provided at their ends with bent; portions 22 formingdove-tail retaining- '95 sockets for removable blocks 23 of material. such as carbon. The flat faces of the conhtly inclined,being lower s closed, the longerl plates being bowed removed vertically' .rom open to closedpo- 1 i :inore than-theshorter so that as the brushes sitiofnthe blocks 23' are first to engage theand inthe o eningmovement of the rush thefblocksfiflarelast toleave'the The longer plates- 21- are";

posts-.1 Bytliisg mean$any b' rning of the.

post 34 extending out from cam-plates 35, and is mounted passes slidably through a gui a lower end-portion 41 orizontal position between brushes, due to the formation of arcs upon 0 ening the'switch, is confined to the renewa le blocks 23.

The laminated brushes are carried by a vertically extending rod 24, which extends through central openings in the brushplates, said rod being threaded and having thereon pairs of nuts 25 between which the plates are clamped, and suitable washers and bushings of insulating material 26 being provided and arranged as shown in Fig.

6, whereby the brushes are insulated from the rod. A metal washer, held beneath the upper clamp-nut 25 of the lower brush," has an integral finger 27 extending therefrom back toward the base 8, the end of said finger being notched and fitting slidably over a guide-rod 28 secured to the base, as shown in Fig. 6, said finger and guide-rod being em loyed to prevent rotation of the rod 24. elow the lower brush the rod 24 has a smooth or unthreaded )ortion which e-post 29, and

eneath said post the terminal portion of the rod is threadedto receive the contoured wedge-body 30 of the variable-tension devlce, which will be fully described hereinafter. On the threaded portion of the rod 24, above the upper brush, a sleeve 31 is screwed and retained fixedl by means of a set-screw 32 passing through the side thereof. A roller 33, mounted revolubly on a the base, bears against one side of the sleeve 31, forming an anti-friction guide therefor. At the opposite side'of said sleeve the same carries a pair of laterally extending cam-plates 35 having contoured ed es of which the upper portions 36 are paral el with the rod 24, and the lower portlons 37 curve inwardly toward the rod. Between the upper portions of said cam-plates there is afiixed a detentbar 38 for retaining the main-switch in open osition, said detent-bar being engageable y a latch-hook 39 when the rod 24 and its attached arts are in the raised position shown in ig. 4. The latch-hook 39 extends in a nearly vertical position between the pivotally uponja post 40 carried upon the base 8. An extended tail-portion on the latch hook has turned outwardl from the sleeve 31, for a purpose which wi l presently ap ear. The latch-hook is impelled inwar l or toward the detent-bar 38, by means cr a spring 42 connected therewith through' the medium of the controlswitch arm 43'. Said arm is secured to the latch-hook and ivot-post 40, the arm extending in a nearly the rod 24 and the face of the base-slab 8, and carryin at its end aybar of insulating material 44. The lower end of the spring 42 is attached to a metal contact-strip 45 secured on the rear and moves therewith about the springs being side of the bar 44, and the upper end of the spring is attached to a hook-plate 46 secured on the base, as shown. The contact-strip 45 is adapted for engagement with a pair of slitted resilient contact-fingers 47 and 48 which are mounted on the base and connected, respectively, with binding-posts 49 Above the sleeve 31 the rod 24 has a smooth or unthreaded portion on which the tubular solenoid-core 51 is slidable. Said core is flattened at one side near the lower end thereof, and a stop-post 52 is arran ed on the base 8 so as to extend alongsice said flattened part, to thereby prevent rotation of the core, and also to limit downward movement of the core by engaging the shoulder formed at the upper end of the flattened portion. At the side of the core opposite the flattened portion there is a lug 53 to which is pivotally connected the upper end of a U-bar 54 which extends downward around the front and rear sides of the core and of the sleeve 31, the lower horizontal part of the bar resting against the contoured edges of the cam-plates 35. The u per end of the core 51 fits slidably within the lower part of a solenoid comprlsing a suitably insulated coil 55 wound upon a spool formed by a sleeve 56 and upper and lower endplates 57 and 58, said end-plates bein secured to the base-slab 8, and the terminals of the coil being attached to binding-posts 59and 60. The upper end-plate has an integral tubular portion 61 extending down inside the sleeve 56. The rod 24 has an upper terminal portion of reduced diameter, which )asses slldably through the part 61, the ro projecting beyond the upper endplate of the spool and being engageable with a cushioning facing-disk 62 carried by a bracket 63 mounted on the base 8 above the solenoid, the structure forming a stop for limiting upward movement of the rod and the core, under the impetus given the latter when the solenoid is energized. lVithin the sleeve 56 of-the solenoid-spool, above the end of the core 51, a collar 64 is screwed on the rod 24, as shown in Fig. 4, said collar forming an abutment against which the core may strike to lift the rod.

Referring now to the variable-tension device at the lower end of the switch-rod 24, the guide-post 29 has on opposite sides thereof pairs of lugs 65 between which are ivoted the upper ends of levers 66. Said levers carry at their lower ends rollers 67 which engage opposite sides of the contoured wedge-block 30, being pressed yieldingly against the same by means of a plurality of s rings 68 of the form shown in detail in ig. 2, the inwardly turned ends of said inserted in holes formed in the outer sides of the levers 66. Said springs, being symmetrically formed at their opposite sides, press in equally upon the levers, so that the pressure of the rollers upon the wedge-body is equalized at the two sides of the body, and thus will have no tendency to move the same laterally. It will be apparent that the inward pressure of the rollers upon the inclined surfaces of the wedge-body will have a tendency to push the wedge-body and rod 24 downwardly when the rollers are in engagement with an upwardly tapering portion of the body, and that the amount of pull or tension thus exerted upon the rod will vary according to the taper of the wedge-body at the points engaged by the rollers. Thus, by suitably contouring the wed e-body, any desired tension upon the switc -rod may be exerted at any portion of its travel, and the movement of the rod assisted more or less as may best suit the operation. In the structure shown, the lower portion of the body 30 is flared so as to ofi'er increased resistance to upward movement of the rod when the latter approaches its upper limit of movement, and to have a corresponding tendency to promptly initiate downward movement of the-rod when the same is released. The intermediate portion of the body 30 has a gradualtaper, so that the tension upon the rod is moderate during the intermediate portion of its travel. Near the upper end of the body 30 the inward taper thereof is abruptly increased, and the same is then slightly flared, the least width of the body being at the point reached by the rollers when the rod is at the lower limit of its movement. Obviously, in the downward movement of the rod, the tension will be augmented as the rollers engage the abruptly tapered eil'ect is utilized for bringing the switchbrushes into firm engagement with the contact-posts, and bending the brush-plates. Contrariwise, the spring of the brushes assists in overcoming the resistance of the wedge-body to upward movement of the rod at the beginning of the switch-opening movement, while the slightly tapered intermediate portion of the wedge-body causes but slight (resistance to the intermediate part of-the upward travel of the rod.

To illustrate theoperation of the switch mechanism, it will be assumed that the motor M is used to drive a compressor for a refrigerant; that .it is desired to start the operation of the compressor when the temperature of a refrigerated chamber reaches a determined maximum, and to stop the operation of the motor and compressor when the temperature of the chamber has been reduced to the desired degree. A thermostat T, placed in the refrigerator-chamber, has stationary contacts 69 and 70 and an intermediate movable arm 71 which is impelled toward the contact 69 by arise of portion of the body, and this temperature, and toward the contact 70 by a decrease of temperature. The contacts 69 and 70 are electrically connected, through the binding-posts 49 and 50, with the control-switch contact-fingers 47 and 48, respectively. The thermostat-arm 71 is connected with a source of electrical energy, as to one side of the supply-circuit for the motor, and the other side of said source is connected with one terminal of the solenoid coil, as by a conductor '(2 connecting the binding-posts 14 and 60. The other terminal of the solenoid coil is connected by a conductor 73 with the hook-plate 46, the latter being connected by the spring 42 with the contact-strip 45 of the control-switch. The main-switch being in the closed position shown in Fig. 1, the latch-hook 39 is held outby the detent-bar 38, so that the arm 43 is in a lowered position at which the contact-strip 45 engages the finger 48. it now the thermostat-arm 71 moves into engagement with the contact 70, a circuit through the solenoid is closed, the solenoid is energized, and the core 51 is thereby pulled upwardly. The upper end of the core 51, engaging the collar 64, lifts the switch-rod 24. Said upward movement of the rod is resisted by the weight of the parts carried thereon, and also by the downward thrust of the spring-pressedrollers 67 on the wedge-block 30. The upward movement is assisted initially, however, by the straightening of the resilient brush-plates of the main-switch, the reaction of said plates being eilective simultaneously with the movement of the rollers 67 over the abruptly inclined portions and onto the moderately inclined or tapered portions of the wedgeblock 30. At the conclusion of the upward movement of the switch-rod, the detent-bar 38 passes the ledge or offset of the latchhook, so that the latter may drop in beneath the detent-bar, and the spring 42 raises the arm 43 to so move the latch-hook, and to simultaneously open the solenoid controlcircuit by moving the strip 45 out of engagement with the contact 48 and into engagement with the contact 47. Upon deenergization of the solenoid, the core 51 drops to the lower position thereof shown in Fig. 4, but the main-switch is held open by the latch-hook. It now, the thermostat arm 71 be moved to engage the contact 69, the second control-circuit is completed and the solenoid again energized to liit the core 51. As the core commences to move upward the lower horizontalportion of the U-bar 54 passesunder the outwardly turned tail-piece 41 of the latch-hook, and as the movement continues the inclined edges 37 of the cam-plates 35 cause the U -bar and latch-hook to swing out laterally from the rod 24, as shown by dotted lines in Fig. 4, thereby disengaging the hook from the deill) tent-bar 38 and releasing the rod 24 for downward movement to the switch-closing position. The lateral movement of the latchhook moves the control-switch arm from the raised position back to the lowered position thereof shown in Fig. 1, thus opening the second control-circuit at the contact-finger l7 and strip 45, but reestablishing the first control-circuit except at the thermostat contacts.

It will be seen that the work of the solenoid in releasing the latch-hook, to en able closing of the switch, may be less than that necessary in opening the switch, but that the energization of the solenoid will be automatically proportioned to the required energy-output therefrom. Thus, in both the switch-opening and switch-closing operations, the completion of the effective movement of the solenoid-core is immediately followed by movement of the latch-hook and control-switch to open the energizing control-circuit, and in neither instance can the control-circuit be opened to cause deenergization of the solenoid until actuation of the main-switch parts has been completed or so initiated as to be automatically completed. M

The variable-tension device applied to the lower end of the switch-rod 24, as described, enables resistance to upward movement of the switch-rod to be so apportioned in the several parts of the stroke as to best suit the operating conditions, giving due consideration to the effective pull of the solenoid-core at different parts of its stroke, and to the resistance of the core-movement offered by the other parts of the mechanism. Thus said tension device contributes materially to smoothness and certainty of operation of the mechanism, with a solenoid of minimum size and cost of construction.

Now, having described my invention, what I claim and desire to secure by Letters Patent is:

1. In an automatic electric switch, a switch member movable reciprocatingly between a circuit-opening and a circuit-closing position, variable-tension means connected with said member and tending to move the same to one position, electromagnetic actuat1ng means for moving said member to the other position, a latch engageable with the member for retaining the same in the latter position, and means movable by said actuating means for disengaging the latch to release the switch-member.

2. In an electric switch of the class described, a rod mounted to reciprocate longitudinally, resilient brushes carried thereby, contacts engageable by said brushes, variable-tension means connected with said rod and adapted to hold said brushes in stressed form against said contacts, electromagnetic actuating means for moving the rod to disengage the brushes from the contacts, mears for holding the rod in the position to which it is moved by said actuating means, and means for releasing said holding means.

In an electric switch of the class described, a reciprocating main-switch member, yieldable tensioning means connected with said member and tending to move the same in one direction, electro-magnetic actuating means for moving said member in the other direction, control-circuits for said electro-magnetic actuating means, a controlswitch for said circuits, a latch connected with said control-switch and movable therewith, said latch being engageable with the main-switch member for preventing movement thereof by the tensioning means, and a releasing member controlled by the electromagnetic actuating means and engageable with the latch when the latter is engaged with the main-switch member, said releasing member adapted to move the latch to a release position and to move the control-switch to reverse the control-circuit connections.

4:. In an electric switch of the class described, a solenoid, two control-circuits therefor, a control-switch arranged to establish said circuits alternatively, a core movable in one direction by energization of said solenoid and biased to move in the opposite direction upon deenergization of the solenoid, a main-switch member actuatable by movement of said core in the direction first named, tensioning means opposing movement of said main-switch member by said core, a latch for holding said switch member in the position to which it is movable by said core, and means actuated by the core for moving said latch to a release position, said latch and the control-switch being connected for reciprocal actuation.

5. .In an electric switch of the class described, a main switch having fixed contacts, flexible brushes engageable with said contacts, a slidably mounted rod carrying said brushes, electromagnetic means for actuating said rod to move the brushes away from the contacts, and variable-tension means connected with the-rod for actuating the same to move the brushes into engagement with the fixed contacts and to flex the same thereagainst, said variable-tension means arranged to exert an increased force upon the rod during the brush-flexing portion of its travel.

6. In an electric switch ofthe class described, a reciprocating main-switch member, means biasing said member to movement in one direction, electromagnetic actuating means for moving said member in the other direction, control-circuits for said electromagnetic actuating means, a control-switcharranged to establish said circuits alternatively, and a holding element connected to and movable with said control-switch, said holding element being engageable with the reciprocating main-switch member when the control-switch is in position to establish one control-circuit, and said holding element arranged to release the main-switch member simultaneously with movement of the control-switch to open the last-named controlcircuit and establish the other.

7. In an electric switch of the class described, a reciprocating switch-member, resilient brushes carried thereby, contacts engageable by said brushes, means for moving the switch-member to a position at which the brushes are held away from the contacts,

means for holding the switch-member in said position, means for moving said holding means to release the switch-member, and a variable-tension device connected with the switch-member and tending to move the same to a osition at which the brushes are engage with the contacts and flexed thereagainst said variable-tension device comprising a wedge-body contoured symmetrically at its opposite sides, a pair of rollers engaging the contoured sides of the body, and means for pressing said rollers'against said bod y H. A. HOESCHEN. 

